We provide a complete answer regarding what social choice functions can be rationalizably implemented.

We analyze the structure of a society driven by power relations. Our model has an exogenous power relation over the set of coalitions of agents. Agents determine the social order by forming coalitions. The power relations determine the ranking of agents in society for any social order. We study...

We analyze the structure of a society driven by power relations. Our model has an exogenous power relation over the set of coalitions of agents. Agents determine the social order by forming coalitions. The power relations determine the ranking of agents in society for any social order. We study...

In order to identify expertise, forecasters should not be tested by their calibration score, which can always be made arbitrarily small, but rather by their Brier score. The Brier score is the sum of the calibration score and the refinement score; the latter measures how good the sorting into...

Objects of different quality are to be allocated to agents. Agents can receive at most one object, and there are not enough high-quality objects for every agent. The value to the social planner from allocating objects to any given agent depends on that agent's private information. The social...

We study information design with multiple privately informed agents who interact in a game. Each agent's utility is linear in a real-valued state. We show that there always exists an optimal mechanism which is laminar partitional and bound its ``complexity''. For each type profile, such a...

A sender designs an information structure to persuade a receiver to take an action. The sender is ignorant about the receiver's prior, and evaluates each information structure using the receiver's prior that is the worst for the sender. I characterize the optimal information structures in this...

Decision theory can be used to test the logic of decision making---one may ask whether a given set of decisions can be justified by a decision-theoretic model. Indeed, in principal-agent settings, such justifications may be required---a manager of an investment fund may be asked what beliefs she...

Rationalizability is a central concept in game theory. Since there may be many rationalizable strategies, applications commonly use refinements to obtain sharp predictions. In an important paper, Weinstein and Yildiz (2007) show that no refinement is robust to perturbations of high-order...

Modern economies rely heavily on their infrastructure networks. These networks face threats ranging from natural disasters to human attacks. As networks are pervasive, the investments needed to protect them are very large; this motivates the study of targeted defense. What are the 'key' nodes to...